Elevator safety controls



Feb. 9, 1960 c. BRANDON ELEVATOR SAFETY CONTROLS Filed Sept. 25, 1956 4Sheets-Sheet l IN V EN TOR. CWPL 5214/1 00 Feb. 9, 1960 c. BRANDON2,924,297

ELEVATOR SAFETY CONTROLS Filed Sept. 25, 1956 4 Sheets-Sheet 2 VINVENTOR C994 ERR/V00 Feb. 9, 1960 c. BRANDON 2,924,297

I ELEVATOR SAFETY CONTROLS Filed Sept. 25, 1956 4 Sheets-Sheet 3 i l p II I l l l i IN V EN TOR.

(H/9A BAA/VDO/V Feb. 9, 1960 c. BRANDON 2,924,297

ELEVATOR SAFETY CONTROLS Filed Sept. 25, 1956 v 4 Sheets-Sheet 4mvgNToR. 04,94 ERA/v0 04 A TTO/P/Vifi United States Patent ELEVATORSAFETY CONTROLS Carl Brandon, Detroit, Mich, assignor, by mesneassignments, to Elevator Construction & Service (10., Detroit, Mich., acorporation of Delaware Application September 25, 1956, Serial No.612,033

3 Claims. Cl. 187-28) The present invention relates to an elevatorsafety control, and more particularly to an elevator control devicewhich fails safe by gravity actuation in response to any one of severaloperating conditions constituting safety hazards.

This application is a continuation-impart of my earlier copendingapplication, Serial No. 540,455, filed October 14, 1955 and abandonedupon the filing of this application.

The use of hydraulic elevators has been limited by the difficulty insafely controlling their operation. A loss of hydraulic pressure, asupon valve failure or cylinder rupture, can have disastrousconsequences. Less spectacular, but equally dangerous, is a gradualuncontrolled descent of the elevator car from an open hatchway door. Theloss of electric power, for driving the hydraulic pump, also can haveserious after effects.

The present invention provides a new, novel, and extremely effectivesafety control system for an elevator. This system is equally applicableto either electrically or hydraulically operable elevators, but thesystem is illustrated and described herein as specifically applied to ahydraulic elevator.

Generally, this system employs a brake applicable to a safety cable orrope attached to an actuating arm for dogs engageable with the hatchwayguides of the elevator car. If the car is descending and the cable ishalted, the dogs will engage the guides to stop the car abruptly andpositively.

The brake means, in the preferred and illustrated form of the invention,includes a brake shoe engageable with the cable as it is lapped aboutthe periphery of a guide sheave or the like, the shoe being movableeccentrically of the sheave so as to be self-energizing when released.Thus, the brake fails safe when released, since it is overbalancedtoward an applied position but restrained from application by thecontrol system.

The brake restraining means biases the brake from application by the useof an electromotive or other force overcoming the graviational applyforce constantly ex erted on the brake. Interruption of the restrainingforce by any means will apply the brake, and this interruption can beaccomplished by or in response to any number of operating conditions.

I have found that interruption of the restraining force and resultantapplication of the brake in response to the following operatingconditions will be sufficient to safeguard users of the elevator:

(1) Actuation of a manual emergency switch.

(2) Loss of hydraulic pressure.

(3) Loss of electric power.

(4) Uncontrolled car descent from a hatchway opening.

(5) Excessive car down speed.

It is,'the'refore, an important object of this invention to provide anew and improved safety control system for an elevator.

Another important object is the provision vofan ele- See 2 vator safetycontrol which fails safe in response to dangerous operating conditionsthrough the application of a positive braking element.

A further object is to provide an elevator control in which a normallygravity-applied brake is restrained from application by a control systemsensitive to any one of several dangerous operating conditions.

it is still another object of this invention to provide a control for anelevator in which the descent of an elevator car is accommodated by therelease of a brake through an electrical control circuit incorporatingelectromotive force means energized only under normal operatingconditions and operative to release the brake for self-energizedapplication upon interruption of the control circuit.

Yet another object is the provision of an elevator control systemresponsive to any one of several operating conditions, includingactuation of a manual switch, a loss of hydraulic or electricalactuating forces, uncontrolled car descent, or excessive car down speed,to immediately and positively halt the car in the hatchway.

On the drawings:

Figure 1 is a schematic representation of the hydraulic actuating systemfor an elevator employing a safety corn trol system of the presentinvention;

Figure 2 is a broken, elevational, somewhat diagrammatic illustration ofa complete elevator actuating mechanism utilizing the safety controlsystem of the present invention;

Figure 3 is an enlarged elevational view of one form of a specific brakemechanism utilized with the elevator of Figure 2;

Figure 4 is a different form of brake mechanism similar to thatillustrated in Figure 3;

Figure 5 is a fragmentary elevational view further illustrating thedetails of connection between the safety control cable and the dogactuation arm of the elevator;

Figure 6 is a wiring diagram illustrating the brake actuation system forutility in connection with the em bodiment of the brake shown in Figure3 of the drawings;

Figure 7 is a Wiring diagram similar to that of Figure 6 butillustrating the control circuit utilizable in connection with the brakeillustrated in Figure 4 of the drawings. 1

As shown on the drawings:

In Figure 1, reference numeral 10 refers generally to the actuatingpiston of an elevator indicated at 2th in Figure 2, the piston beingvertically operable within a cylinder 11.

The cylinder 11 receives pressured fluid from a pump 12, which ispreferably electrically driven to transfer fluid from a reservoir orcontainer 13 and through a one way check valve 14 and a passage 15 tothe cylinder 11.- A gate valve 16 controls the flow of fluid through areservoir return line 17, the valve 16 being controlled through alinkage 19 actuated by a solenoid 18. The solenoid 18 and its associatedvalve 16 form a part of the conventional hydraulic elevator controlmechanism, and as such form no part of the present invention. A handpump 19a located between a pair of one way check valves may be utilizedfor manually raising the elevator in the event that power actuation ofthe pump 12 failsor to lift the elevator off the dog stop (hereinafterdescribed) in the event of power failure.

As best shown in FigureZ, the piston 10 is connected directly to thefloor or platform 20a of the elevator 20, so that, upon operation of thepump 12 to fill the cylinder 11 with pressured fluid, upward movement ofthe cylinder 10 will effect elevation of the platform 20a. Alternately,upon actuation of the solenoid 18 and turning of the gate valve 16,fiuid from the cylinder will be bled back through the passages 15 and 17into the reservoir 13 to accommodate lowering of the platform 20a.

Vertical movement of theplatform 20a is guided by a pair of verticallyextending, laterally spaced guides 21 having a central vertical rib 21aengaged by vertically spaced guide elements 22 on the elevator platform20a and carried by spaced vertical .posts 22a forming apart of theelevator 20.- It will be appreciated that in Figure 2, only one verticalguide21'is illustrated, but it will be evident that two such guides areprovided in laterally spaced relation and an additional set of guideelements 22 are provided for engagement with the other guide 21.

A safety cable or rope 23 is attached to the elevator 20 through anattachment bracket 24. The cable 23 forms, in efiect, a closed loop andis lapped about vertically spaced sheaves or the like 25 and 26 whichare disposed adjacent the upper and lower extremities, respectively, ofthe elevator travel. The upper sheave 25 is disposed upon a lateralshaft 25a which is supported upon uprights 25b which, in turn, aremounted upon a :structural member 25c forming a part of the building inwhich the elevator is utilized. The other sheave 26 is disposed upon ashaft 26a journaled in a vertically slidable frame 26b which is freelymovable on vertical support rods 26c carried by arms 26d projectinglaterally from the guide posts 21. The Weight of the sheave 26 and itscarriage 26b maintains the cable 23 taut.

The actual connection of the cable 23 with the elevator car 20 is bestshown in Figure 5, from which it will be seen that the connecting arm 24is provided with an aperture 24a through which a vertically slidable rod24b extends. This rod 24b carries an abutment 24c and confined betweenthe abutment 24c and the arm 24 is a coiled compression spring 24d whicheffectively urges the rod 24b downwardly to the position shown in Figure5.

The lower end of the rod 24b is connected to adog actuation arm 24c, theother end of the arm 24e being keyed to a shaft 24 which extendstransversely of the elevator 20 to carry at either extremity thereof adog 24g engageable with the vertical rib 21a of the vertical guides 21.Obviously, counterclockwise movement of the lever 24e will cause thesame movement of the dogs 24g, so that the dogs will engage the rib 21ato prevent further downward displacement of the car 20. The upper end ofthe rod 24b is connected to both ends of the cable 23, as at 23a and23b.

The operation .of the dogs will be readily appreciated, since halting ofthe cable 23 and continued downward movement of the car 20 will causethe cable 23 to move the rod 24b upwardly against the compression of thespring 24d, thus causing counterclockwise movement of the lever 24a andthe dogs 24g, so that the dogs engage the guide rib 21a. scent of theelevator car 20 will be prohibited. Once the cable 23 is again releasedfor movement, the spring 24d will return the arm of 24a to itsillustrated position, and the dogs 24g will be released.

The braking means for the cable 23 is illustrated in Figures 3 and 4 ofthe drawings, wherein it will be seen that a self-energizing brake shoe27 is disposed upon a brake actuating arm 27a, the arm 27a being in theform of a yoke straddling the pulley or sheave 25 and being pivotalabout a pivot axis 29a which is displaced vertically from the shaft 25aof the sheave 25. Movement. of the yoke 29 about the center 29a willcause the brake shoe 27 to move toward the periphery of the sheave 25.The sheave 25 is, of course, grooved to receive the cable 23 thereabout,and the shoe 27 is of such size as to fit in this groove and to engagethe cable 23. After engagementbetween the shoe 27 and the cable 23,further continued clockwise rotation of the sheave 25 will serve tofurther engage the brake shoe 27 with the cable 23. Thus, the brake shoe27 is said to be self-engaging.

Preferably, the arms 29 oi: the yoke carrying the shoe 27 are keyed to ashaft'29b which defines the pivot axis for the yoke, and alsosecuredto-this shaft 29b is a laterally extending, generally triangularlever 30. That Thus, downward movement or deface of the lever 30 remotefrom the shaft 29b is .arcuate, so as to be concentric with'the axis29a, and the face is provided with gear teeth 33. The teeth 33 meshwitha sector gear 33b mounted upon the driven shaft 33a of a torque motor 31which is energizable through electrical lead lines 32 in a manner. to behereinafter more fully described.

The lever 30 is of such size and weight that it is gravitationally urged.in a clockwise direction. This weight of the lever 30 biases the yoke29in a clockwise direction and thereforebiases the brake shoe 27 towardengagement with the cable 23. If the lever 30 were not a 23 could notaccommodate downward movement of the elevator car 20, since therestraint against this movement of the cable would constantly apply thedogs 24g.

The yoke 29 can also be moved so asto apply the brake shoe 27 to thecable 23 by a plurality of centrifuw gally actuated dogs or levers 28..These dogs 28 are pivoted to the sheave 25and :are movable radiallyoutwardly in response to excessive rotational speeds of the sheave toengage the inner surfaces of yoke 29 urging it clockwise overcoming theelectrical or other holding means and thereby apply the brake. 1 Suchcentrifugal actuation ofthe brake is conventional and is not claimed asa feature of the present invention.

The wiring diagram of Figure 6 of the drawings shows the control for thetorque motor 31. The windings of i z the motor 31 are illustratedschematically in the circuit as being energized by the three lead lines32 hereinbefore described. This torque motor is of conventional type andis designed to exert a predetermined rated torque without danger to themotor when the motor is stalled.

:1: The motor 31 is of a capacity and torque rating such that 0% isde-energized, the weight of the lever 30 will apply the it can exert atorque sufficient, when acting through the.

gears 33 and 33b, to prevent the application of the brake 27 to thecable 23. So long as the motor 31 is energized,

the brake will not be applied. However, once the motor brake. i

Thus, the torque forceof themotor restrains the brake from application,the electromotive force of the motor overcoming the gravitational applyforce constantly errerted on the brake by the lever 30. As illustratedin Figure 6, several abnormal operating conditions may be utilized tointerrupt the actuation of the motor 31 so as to apply the brake.

More specifically, in Figure 6 current applied to the windings of themotor 31 from one of the lead lines 32 passes through a pair of relaycontacts 40 which are under the control of a. relay R1. Thisrelay R1 isin circuit with a pair of contacts 41 which are adapted to be closed bya pressure responsive switch 42 having a cylin- 7 der 42a subject to thepressure in they hydraulic conduit out of contact with the contacts 41by a compression 15 (Figure 1)'. So long as hydraulic pressure ispresent in the conduit 15,piston 43 is depressed to close the contacts41. Once the pressure in the conduit 15 falls below a predeterminedminimum, the piston 43 is urged spring 44. Thus, a failure of hydraulicpressure in the conduit 15 will de-energize the relay R1 to open therelay 3 contacts 40, thus de-energizing the motor 31 and allowing thebrake 27 to be applied by the gravitational lever 30. To insure settingof the brake even when the pressure loss is momentary, a holding circuitcan be provided for the relay R1.

A different phase of the motor 31 is energized through a manualemergency switch 45 which is normally closed,

- but which can beopened by the elevator operator ora passenger in theelevator to de-energize the. motor 31 and apply theebrake 27.1 i

To further control the operation of the elevator, specifically to haltthe elevator in the event of a gradual leak in the system such that theelevator may drift downwardly or gradually settle from an open hatchwaydoor, a cam actuated limit switch 46 is provided. This switch 46 is inparallel with a pair of elevator movement control switches 486T and 48b,which control the downward and upward movement of the elevator throughthe solenoid 18 for controlling the gate valve 16 and through the pump12.

The switch 46 is controlled by a cam follower arm 47 (Figure 2) which ismounted on the car beneath the platform 20:! thereof for contact with acam surface 48 attached to a floor or other elevator station 50 of thebiulding in which the elevator is movable. So long as the switch 46 isclosed by the cooperation of the cam 48 with the cam arm 47, the brake27 will not be applied, inasmuch as the motor 31 is still operable.Thus, the brake is not applied when the elevator is stopped at a floor50 and neither the upswitch 4811 nor the downswitch 48b is closed.However, in the event that neither the switch 48a nor the switch 48b isclosed and the elevator platform drifts downwardly sufiiciently toremove the arm 47 from the cam 48, the switch 46 will be open and thecorresponding phase of the motor 31 will be deenergized, thus cuttingoff the motor and accommodating the gravity application of the brake 27to the cable 23.

In that embodiment of the invention illustrated in Figures 4 and 5,identical reference numerals refer to identical portions of theapparatus illustrated in Figure 3 of the drawings. It will be noted thatthe triangular geared lever 30 has been replaced with a straight lever36 which cooperates with the yoke 29 to define a bell crank controllingapplication of the brake 27 to the cable 23. This lever 36 isoverbalanced in the same manner as the lever 30 heretofore described,and the lever is retained against clockwise movement by a solenoid 34connected to the extreme end of the lever 36 through a link 35.

The solenoid 34 is adapted to be energized through a circuit illustratedin Figure 7 of the drawings. It will be noted that this circuit againincludes the pressure switch 42 and the relay R1 for controlling therelay contacts 40. Here, however, the relay 34 is provided with an upperswitch plate 51 adapted to close contacts 52 when the relay isde-energized, which contacts form a switch for shorting out a relayresistance 53 which is in the circuit through the emergency switch 45and the cam switch 46. The solenoid switch 51-52 is normally open whenthe solenoid coil 54 is energized. Thus, current from the switches 45and 46 and through the contacts 40 must necessarily pass through theresistance 53 36. The smaller current flow through the resistance 53 issuflicient to retain the arm 36 in its elevated position.

I claim:

1. In an elevator construction having a plurality of elevator stationsand elevator braking means, control circuit comprising elevator up anddown switches which are closed respectively for moving said elevator upand down, switch means, tripping means, said tripping means beingengaged with said switch means to close said switch means when saidelevator is at a station and disengaged when said elevator has moved anincrement away from said station, a power circuit including power meansfor restraining application of said elevator braking means, saidelevator up and down switches and said switch means being in said powercircuit with said circuit being broken when all of said switches andswitch means are open but closed when any one of said switches or switchmeans is closed.

2. A' safety control for an elevator car actuatable vertically along aguide rail, comprising a brake dog on the car engageable with the rail,a cable operatively connected to the brake dog to apply the dog uponhalting of the cable and continued descent of the car, a fixed axissheave passed over by said cable, a self-energizing cable brake armmounted on a parallel fixed axis spaced from said sheave fixed axishaving a brake shoe adapted to brakingly engage said cable while passingaround said sheave, a lever arm connected to said brake arm biased tourge said brake arm and shoe into braking position, an electric torquemotor operatively connected to said lever arm adapted when energized tohold said brake arm and shoe in a disengaged position and whende-energized to permit movement thereof to said braking position, anenergizing circuit for said torque motor, a plurality of safety controlswitches interposed in said energizing circuit the opening of any one ofwhich in response to any of a plurality of different emergency operatingconditions such as uncontrolled car descent from a normal stoppingposition or manual actuation of an emergency switch in the elevator carwill de-energize said torque motor causing engagement of said cablebrake, halting of said cable, actuation of said brake dog and braking ofsaid elevator car. 7

3. A safety control as set forth in claim 2 applied to an elevatoractuated by hydraulic pressure wherein means are included for openingone of said safety control switches in response to a drop in hydraulicactuating pressure below a predetermined minimum elevator operatingpressure.

References Cited in the file of this patent UNITED STATES PATENTSSprague Jan. 15, 1935

